 |
 |
|||||||||
 |
|||||||||
A. Acoustic Senses: Hearing: Sharks have only an inner ear, which consists of three chambers and an ear stone called an otolith. A sharks inner ear can detect gravity, sound and acceleration. Sharks sometimes uses sound to locate food and it is usually the first sense a shark would use. Sharks are attracted to low frequency pulsed sounds, similar to that wounded or ill prey would emit. Lateral line: The lateral line is a series of fluid-filled canals just below the skin of the head and sides of the body. It is connected to the outside through small pores. The lateral line contains a number of small sensory cellswhich detects current and turbulence caused by water. the lateral line senses low frequency sounds and functions mainly distance perception and detecting water flow. |
|||||||||
|
|
|
|
|
|
|
|
|
|
 |
|||||||||
The lateral line system with its canals. |
|||||||||
B. Eyesight: Sharks have a laterally compressed eye with a large and spherical lense. Its eyes are particularly sensitive to movement in dim light. Sharks may have some colour vision since they have cone cells in their eyes. At the back of the eyes there is a reflecting layer of cells, called the tapetum lucidum, which reflects the light back again to help it see more effectively.A sharks pupil can dilate and contract and in clear water the shark can see up to 15 m. C. Taste: Sharks and batiods have taste buds in their mouths but these have not been studied extensively. It may help in the final acceptance or rejection of the prey items. D. Smell: The shark have paired external nostrils which leads to the olfactory organs. They have an acute sense of smell and can detect some chemicals in such dilutions as one part in a billion and up to 100 m away. E. Ampullae of Lorenzini: The ampullae of Lorenzini forms a complex and extensive sensory network around the sharks head. External pores cover the surface of the sharks head and each leads to an jelly filled canal connected to a membranous sac called an ampulla. These sacs have sensory cells which detects weak electrical fields over short ranges. They are only effective within a few centimetres, as they sense bioelectrical fields in the final stage of prey capture. The ampullae may also detect temperature, salinity, mechanical stimuli and magnetic fields. |
|||||||||
 |
|||||||||
The ampullae of Lorenzini. |
|||||||||
F. Sensory Pits: A sensory pit is a small depression in the skin which is formed by the overlapping of two enlarged scales. At the bottom of the pit there is a small cluster of sensory cells that resemble a taste bud. the precise function of the sensory pits have not been determined but they may be sense organs. They occur on the back sides and lower jaw of the shark. |
|||||||||